Describe how waste glass can be recycled for a use other than new containers.

It is crushed into cullet, which can be melted for new glass or crushed further for use in road surfacing and insulation.

Explain why recycling aluminium drinks cans saves so much energy.

Melting the metal down uses only a small fraction of the electricity needed to extract new aluminium from its ore.

Why is sorting an essential first step in recycling?

Different materials melt and behave differently, so mixing them would spoil the recycled product.

Give one reason a recycled material is often used for a lower-grade purpose than the original product.

Reprocessing can shorten polymer chains or leave impurities, so the material is weaker or less pure.

OCR GCSE Combined Science Chemistry J250

Chemical Reactions

Topic overview Writing formulae of elements and compounds Balanced equations, and deducing formulae from ions Ionic equations, and state symbols The mole and the Avogadro constant Conservation of mass, and changes of mass in open systems Stoichiometry, and calculating reacting masses Exothermic and endothermic reactions, and reaction profiles Activation energy, and bond energy calculations Oxidation and reduction, by oxygen and by electrons Acids, alkalis and neutralisation The ionic equation for neutralisation, and reactions of acids Dilute and concentrated, weak and strong The pH scale, and hydrogen ion concentration pH as a factor of ten, and measuring pH Products at the electrodes, and molten ionic compounds Electrolysis of aqueous solutions Inert and non-inert electrodes

Elements, Compounds and Mixtures

Topic overview Purity, and melting point data Relative formula mass and empirical formulae Formulations, and separating mixtures Paper and thin layer chromatography Interpreting chromatograms and Rf values Choosing a purification method Metals and non-metals in the Periodic Table Electron arrangement and position in the Periodic Table Ionic, covalent and metallic bonding compared Dot and cross diagrams, and the limits of models Reactions, electron arrangement and Mendeleev's table Carbon's four bonds, and the variety of organic compounds Diamond, graphite, fullerenes and graphene Bond strength, intermolecular forces and predicting state Bulk properties of ionic, molecular and giant structures

Global Challenges

Topic overview Extracting metals by reduction and by electrolysis Biological methods of metal extraction Life cycle assessment Recycling, and the decisions behind it Fractional distillation of crude oil The fractions, and crude oil as a feedstock Dependence on hydrocarbons, and cracking The Earth's early atmosphere, and how oxygen developed The greenhouse effect, and evidence for climate change Effects of carbon dioxide and methane, and air pollutants Producing potable water

Monitoring and Controlling Chemical Reactions

Topic overview Mass of solute, concentration and dilution calculations Measuring the rate of a reaction, and rate graphs Factors affecting rate, and collision theory Surface area and rate Catalysts and how they work Reversible reactions and dynamic equilibrium Changing the conditions of an equilibrium Activation energy, and enzymes as catalysts

Particles

Topic overview The particle model and changes of state Limitations of the particle model How the atomic model changed, and the structure of the atom The size of atoms, and the subatomic particles Calculating protons, neutrons and electrons

Predicting and Identifying Reactions

Topic overview Groups 1, 7 and 0, and why they behave as they do Predicting reactivity from the Periodic Table Reactivity of metals with water and acids Tests for oxygen, hydrogen, carbon dioxide and chlorine

Global Challenges

Recycling, and the decisions behind it

3 things to know
Paper 10 (Chemistry)

Overview

How plastic bottles become fleece and why that is easier than making new bottles, recycling glass and car tyres for other uses, why recycling aluminium saves so much energy, why sorting comes first and recycled material is often lower grade, the resources saved, and the costs, contamination, scarcity, market prices and social factors that decide whether recycling is worthwhile.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What decides whether recycling a material is worthwhile: the environmental cost, the scarcity of the raw material, contamination and market price?

Key term

Describe how used plastic bottles can be recycled into fleece fabric.

Key term

Explain why recycling a drinks bottle into fleece is more viable than recycling it into a new drinks bottle.

Questions from this subtopic

Each one with the model answer underneath.

1
Describe how used plastic bottles can be recycled into fleece fabric.
Model answer
The bottles are sorted, cleaned, shredded and melted, and the melt is drawn into fibres that are spun into fabric.
2
Explain why recycling a drinks bottle into fleece is more viable than recycling it into a new drinks bottle.
Model answer
Fabric does not have to meet food safety standards, so slight contamination and colour in the recycled plastic do not matter.
3
Describe how waste glass can be recycled for a use other than new containers.
Model answer
It is crushed into cullet, which can be melted for new glass or crushed further for use in road surfacing and insulation.
4
Explain why recycling aluminium drinks cans saves so much energy.
Model answer
Melting the metal down uses only a small fraction of the electricity needed to extract new aluminium from its ore.
5
Why is sorting an essential first step in recycling?
Model answer
Different materials melt and behave differently, so mixing them would spoil the recycled product.
6
Give one reason a recycled material is often used for a lower-grade purpose than the original product.
Model answer
Reprocessing can shorten polymer chains or leave impurities, so the material is weaker or less pure.

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Chemical Reactions

Elements, Compounds and Mixtures

Global Challenges

Monitoring and Controlling Chemical Reactions

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AMetals are on the left and in the centre, and non-metals are on the right-hand side.

BKI, because potassium loses one electron and iodine gains one.

CCaCl₂, because a calcium atom loses two electrons and each chlorine atom gains one.

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Sodium ions give a bright yellow flame colour.

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